What vitamin levels should be checked in a female patient on Zepbound (tirzepatide) with significant weight loss and fatigue due to reduced food intake?

Vitamin Level Testing for a Female Patient on Zepbound with Significant Weight Loss and Fatigue

For a female patient on Zepbound (tirzepatide) experiencing fatigue and significant weight loss with reduced food intake, comprehensive testing should include vitamin B12, folate, iron studies, vitamin D, zinc, copper, and selenium levels to address potential nutritional deficiencies.

Primary Vitamin Panels to Check

• Complete B-vitamin panel: Particularly B12, folate, and B6, as deficiencies can contribute to fatigue and are common with reduced food intake 1
• Vitamin D with calcium, phosphate, magnesium, and PTH: Vitamin D deficiency is prevalent in weight loss patients and can contribute to fatigue 1
• Iron studies: Including serum ferritin, transferrin saturation, and complete blood count to assess for iron deficiency anemia 1
• Trace minerals: Zinc, copper, and selenium levels, as unexplained fatigue may be related to deficiencies in these micronutrients 1

Rationale for Testing These Specific Vitamins

B Vitamins

• B12 deficiency can develop with reduced food intake and may contribute to fatigue even before overt deficiency develops 2
• Folate and B6 work together with B12 in important metabolic pathways and should be assessed concurrently 1, 3
• B vitamin deficiencies may not always present with elevated homocysteine, so direct measurement is preferred 2

Vitamin D and Related Minerals

• Vitamin D levels below 50 nmol/L are considered inadequate and may contribute to fatigue 1
• Check calcium levels simultaneously, as tirzepatide has been associated with hypercalcemia in some cases, especially in combination with certain medications 4
• Magnesium and phosphate should be checked alongside vitamin D as they work together in metabolic processes 1

Iron Status

• Iron deficiency is a common cause of fatigue, especially in females with reduced food intake 1
• Complete iron studies (not just hemoglobin) are necessary to detect early iron deficiency before anemia develops 1

Trace Minerals

• Zinc and copper should be tested together as they affect each other's absorption 1
• Selenium deficiency can contribute to fatigue and is often overlooked 1

Special Considerations for Patients on Tirzepatide (Zepbound)

• Patients on GLP-1/GIP agonists like tirzepatide may have altered nutrient absorption and significantly reduced food intake 4
• Significant weight loss (50 lbs) increases risk of multiple micronutrient deficiencies 5
• Monitor electrolytes carefully, as tirzepatide has been associated with electrolyte disturbances in some patients 4

Common Pitfalls to Avoid

• Don't assume fatigue is solely due to caloric restriction - vitamin deficiencies can contribute significantly to fatigue symptoms 1
• Don't overlook trace minerals - zinc, copper, and selenium deficiencies are often missed but can contribute to fatigue 1
• Don't test B12 in isolation - the interrelationship between B vitamins means they should be assessed together 1, 3
• Don't forget to assess vitamin D status - even in non-bariatric weight loss, vitamin D deficiency is common 1

By comprehensively assessing these key vitamins and minerals, you can identify specific deficiencies that may be contributing to your patient's fatigue and develop a targeted supplementation strategy to address them.